This invention relates to an apparatus for combined threshing and separating of seeds from a seed crop of the type which includes a rotor mounted for rotation about an axis with a stator surrounding the rotor and defining therewith an annular channel between an outside surface of the rotor and an inside surface of the stator, means for feeding the crop material into an inlet end at one end of the annular channel for movement between the rotor and the stator to a discharge end axially opposed to the inlet end and means for separating the seeds from the crop material at the discharge end of the annular channel.
Work on an arrangement of this type was carried out in the late 1920s by Curtis Baldwin. He discloses a number of arrangements in his U.S. Pat. Nos. 1,907,035 issued in 1933, 1,911,665 also issued in 1933 and 1,949,774 issued in 1934.
Each of these patents discloses a rotor which is generally conical so as to diverge outwardly or increase in diameter from an inlet end towards an outlet end. A stator surrounds the rotor and has a similar shape so as to define an annular channel there between which also increases in diameter towards the discharge end. An auger feeds the crop material longitudinally of the axis from a feeding system forwardly of the rotor toward an inlet end of the annular channel so that the crop material is injected into the annular channel at the feed end of the rotor and moves with the rotor axially and outwardly from the axis through the annular channel to the discharge end. The rotor and stator carry rasping bars so that the threshing action occurs between the rotor and the stator acting to thresh the seeds out of their connection to the remainder of the crop material.
Downstream of the discharge end of the annular channel, Baldwin proposed an arrangement for separation of the seeds from the remainder of the crop material after the threshing has occurred in the rotor and stator arrangement by a fan which is connected to the rotor and rotates with the rotor so as to draw air radially inwardly against the centrifugal action on the seeds. The fan thus pulls air inwardly toward the axis and longitudinally of the axis away from the discharge end of the annular channel to carry the lighter crop material along the axis to the fan for discharge radially outwardly of the fan while allowing the seeds under the centrifugal force caused by the rotation of the rotor to move outwardly away from the axis against the air movement for collection at a bottom of a housing surrounding the discharge end of the rotor.
However the separation of the seeds from the crop material using simply air flow and the forces generated by the centrifugal action of the rotor is believed to be unsatisfactory leading to the possibility of significant losses of seed in the crop material carried through the fan. The Baldwin threshing machine therefore apparently achieved little success at the time and was unable to displace the conventional arrangement of the combine harvester which has become widely adopted and widely used up till the present time.
The conventional combine harvester utilizes a threshing cylinder mounted with its axis transverse to the direction of feed to the crop material and a concave surrounding a part of the cylinder so that the crop material engages the cylinder and is fed between the outside surface of the cylinder and the concave so that the seeds are discharged away from the cylinder and the remainder of the crop material is carried rearwardly with the cylinder for discharge onto the straw walkers. The cylinder and concave arrangement therefore carries out all of the threshing action and some of the separating action with the remainder of the separating action being effected at the straw walkers. This arrangement has a number of significant disadvantages in that it is relatively complex and in that it is highly susceptible to tilting of the system relative to a nominal horizontal position of the combine harvester.
An alternative technique for the combine harvester comprises the rotary combine in which the cylinder is rotated through 90.degree. so that its axis is longitudinal of the direction of crop movement and the cylinder is increased in length so as to have an increased threshing action. This obviates the necessity for straw walkers so that the threshing and separating action occurs wholly at the rotary cylinder. The rotary combine has achieved some success in recent years but is becoming less popular due to some perceived inefficiencies in some crops.
It has been generally appreciated that both of these combine harvester techniques have a number of disadvantages and could be significantly improved.
Some further work in this area has been carried out by Lagergren and Underwood which is shown in a brief article describing their machine although searches have revealed no patents disclosing details.
Also some research has been done into techniques for threshing and separating using rotating cones.
In one research paper published in 1963 in Transactions of the ASAE, Lalor and Buchele disclose and test an arrangement similar to that of Baldwin using a rotating conical rotor surrounded by a stationary conical cylinder. The separation of the seeds from the crop material also occurred in the annular channel between the rotor and the stator with the seeds passing through perforations in the conical stator.
This arrangement is shown in more detail in U.S. Pat. No. 2,906,270 of Buchele apparently but has not led to any commercial products.
Further research was carried out and published in 1964 in transactions of the ASAE by Buchanan and Johnson. This related to an attempt to effect threshing and separation on the inside of a rotating cone. The crop material was fed into the apex or narrower end of the cone and moved axially and outwardly due to the rotation of the cone with the seeds passing through holes in the cone and the remaining crop material passing along the cone for discharge at the larger open end. The paper appears to relate solely to a research evaluation and did not apparently lead to any commercial equipment.